I'm a senior reporter for the Daily and Sunday Telegraph. This is my personal blog. I'm also cycling commissioner for London, but nothing below represents the view of the GLA or the mayor. For that, go to the official City Hall cycling blog.

During the last mayoral election, there was a newspaper that lost its journalistic bearings. It ran as many as five knocking pieces a day against one of the candidates, some of them childish, some absurdly vitriolic, several of them transparent propaganda. As the next mayor poll approaches, is The Guardian once again at risk of embarrassment?

This week alone, as the campaign gathers speed, The Guardian has published at least two stories about Boris Johnson that – to put it kindly – lack visible means of support. On Tuesday it claimed that Boris had been “lined up” as the Tory candidate for the safe seat of Reigate at the 2015 general election – a hugely damaging allegation, if true, since it would suggest that Boris does not intend to serve a full term if re-elected mayor and that he has priorities other than London.

Sadly, the article contains no source whatever – not even an anonymous quote – for this incendiary claim. What it does contain, however, is a flat, on-the-record denial from Boris that he will run for any parliamentary seat at all. “I really don't see how I can run for Parliament in 2015,” he says. “Let's kill this. I'm ruling myself out.” He also specifically stated that he would serve a full term if re-elected. The quotes weren't even a response to the Guardian’s “story” about Reigate – they appeared in Boris’s Sun interview on Friday. It is hard to see how the Guardian felt able to run a story about something which Boris had so explicitly precluded three days before.

Today, The Guardian published on its website a video which it entitled “Chicken chases Boris Johnson at City Hall”and which one of its senior executives described on Twitter as a “Boris encounter with chicken.” It shows a Boris-like figure on a bike, fleeing from a man dressed as a chicken, but only from the rear. Judging by the reactions online, most people believe it to be what the paper claims – a genuine “encounter” or “chase.”

In fact, the video is a spoof (or, if you want to be harsh, a fake) produced by the Ken Livingstone campaign. As Boris puts it, “this is a chicken that is itself so chicken that it did not have the gumption to find me in person. It is poultry poltroonery on an epic scale.” Team Ken passed the video to its chief media representative on earth, the Guardian’s Dave Hill, who published it without any mention of its provenance.

(Update: In a touching sign of how closely he follows this blog, Dave within the hour changed his page to remove the claim that the video was of Boris – but don't worry, I've got a screengrab. If only I could work out how to put it up…)

Ken’s typically original and intelligent use of a guy in a chicken suit was to highlight Boris’s alleged “failure” to attend election debates. It seems perhaps unkind to mention that there haven’t actually been any debates to attend so far, and that the semiotics seem confused – surely Boris should be the chicken?

This week’s misrepresentations are not serious – but they are interesting as a sign of how the Guardian may intend to play this. It’s an outstanding newspaper – but there has always been something about Boris which drives it completely off its rocker. During the 2008 campaign, it described him as a “sociopath,” a “moneyed creep… from postcode Posh,” a “bigot,” a “snob,” “loathsome,” a “moron” and of course a (gasp) “public schoolboy,” quite unlike anyone at The Guardian, of course.

News stories claimed that Boris was “shunning the hustings” (when he had in fact attended every day that week, except the day the story appeared) and that a “resurgent Mayor [Livingstone]” had “narrow[ed] the gap” in the polls (that day, the polls had gone from a dead heat to Ken six points behind). They even ran a front-page story alerting the public to Boris's "potential conflict of interest" in taking a donation from a developer – without declaring their own actual conflict of interest (one of the journalists who wrote the story had received money from Ken’s City Hall!)

Perhaps the highlight was when one of their columnists tastefully compared the editor of my then newspaper, the Evening Standard, to Goebbels. No one could have been in any doubt who we supported, of course – but our news investigations about Ken were scrupulously accurate, which is no doubt why they won the top award in the profession, and nothing we actually wrote (as opposed to Team Livingstone’s misrepresentations of it) has ever been denied. Our comment pieces were strongly anti-Ken, but they too used facts and arguments, not playground insults and stunts. Maybe the Guardian might like to take note.